Historically, Studley was among the first to associate nutritional status and disease outcome. In 1936, this pioneering investigator made the classic observation that marked weight loss prior to peptic ulcer surgery resulted in a higher post-operative mortality rate relative to weight-stable patients. Modern health care workers have identified weight loss as a major determinant of prognosis in many disease states.
Total health care is contingent upon sound nutritional status. Practicing physicians and physician extenders evaluating the clinical and nutritional status of their patients should be able to implement an effective feeding program when needed. The wide range of nutritional preparations, catheters and feeding tubes available makes it possible to meet the differing requirements of varying pathological states, either accompanying or causing malnutrition.
The enteral route is a primary means of improving nutritional status in most patients. It is simple, economical and tolerated well in most patients. Optimal enteral feeding requirements can be achieved with the large number of enteral formulas available.
Formulas for enteral use can be subdivided into three basic types: elemental, polymeric, and modular. All of the enteral formulas differ in content and source of nitrogen, carbohydrate, fat and other nutrients, osmolality, taste, residue and expense. The formula components are either premixed by the manufacturer, or added together by the nutritionist shortly before administration. All formulas have the potential to have undissolved, condensed, coagulated, amalgamated, intermixed solids resulting in thickening and enteral tube clogging.
Obstruction of enteral feeding tubes is also precepitated by medications added to feeding formulas or administered via the feeding tube. A major problem is undissolved medications being forced down feeding tubes. The increased cost of injectable or liquid forms of medications and the accessibility to oral tablets is seen as the reason for this ongoing problem.
Feeding tube design has also been associated with higher occurrence of clogging. The small caliber feeding tubes are frequently occluded by feedings and/or medications. The addition of an irrigation port can lower the work to flush the feeding tube and may result in a reduction in obstruction. Medical grade components of the tubes, polyurethane, polyvinylchloride, silicone, etc. do not seem to make a difference in occlusion rates. Large exit ports have been added with claimed advantages, but obstructed enteral feeding tubes is still a major problem. Standard feeding systems provide high rates of feeding in the range of 800 to 1200 ml. per hour. These rates are adjusted with a clamp or pump in normal patient feeding. In jejunal feeding high rates are not desirable and the standard feeding equipment is not advantageously employed.
The added cost of a new tube, nursing time, and x-ray; possible complications of the tube placement; and concern about interruption of feeding to the patient have provided the impetus for developing new devices and methods to clean and open clogged feeding tubes and now to help prevent obstruction of feeding tubes.